D.M.
Have a discussion with her doctor about this. After that, I would add more fiber as suggested by others. Before you try medication and stuff she may not eat like broccoli, see that she eats two apples a day. Apples have both soluble and insoluble fiber in them in just the right balance to give one a perfect stool sample. And apples don't give you diarrhea or abdominal cramping like laxatives or fiber supplements.